OKAY. IF YOU'RE TAKING THE TRAINS, YOU'RE STILL RUNNING ON TIME. THANK YOU. RIGHT NOW, INVESTIGATORS ARE TRUEING TO FIGURE OUT WHAT STARTED A FIRE THAT COMPLETELY DESTROYED A BUILDING IN CHELMSFORD. AND JOHN ATWATER IS THERE. THIS PAY MAY BE SUSPICIOUS? POLICE SAY THIS BUILDING HAS BEEN BROKEN INTO BEFORE. YOU CAN SEE FIREFIGHTERS IN THE DISTANCE, SO THIS MORNING NOT CLEAR WHY THE FIRE STARTED BUT FIREFIGHTERS AT THIS POINT ARE NOT RULING ANYTHING OUT. THE FLAMES ROLLED THROUGH THE LARGE OLD BRICK BUILDING OFF PRINCETON STREET, CHEWING THROUGH INTERIOR WALLS AND MAKE IT A CHALLENGE FOR FIREFIGHTERS TO CONTROL THE FLAMES. IN THIS VIDEO, YOU CAN SEE THE FIREWALL FIREFIGHTERS WERE UP AGAINST WHEN THEY ARRIVED AROUND 10:30. IT WAS PART OF THE WEB CAMPUS BUT RECENTLY HAD NOT BEEN USED TO FIREFIGHTERS KNEW THERE WAS LIKELY NO ONE INSIDE BUT CALLED THREE ALARMS BECAUSE EMBERS FROM THE FIRE WERE TRAVELING. IT TOOK MORE THAN AN HOUR TO CONTROL THE FLAMES AND LONGER TO TAKE CARE OF HOT SPOTS. THE WALLS ARE STILL STANDING, BUT THERE IS VIRTUALLY NOTHING LEFT INSIDE. A PRETTY TOUGH FIRE TO FIGHT OVERNIGHT. FIREFIGHTERS STILL HERE, STILL LOOKING FOR A CAUSE.

Lawyers for Boston Marathon bomber Dzkokhar Tsarnaev rested their case in his federal death penalty trial Tuesday after presenting a brief case aimed at showing his late older brother was the mastermind of the 2013 terror attack.